In order to measure the intrinsic reaction rate constant, an amount of 10 mg of copper concentrate Particles was sprayed in alumina wool and it was heated up to 1000K in an O_2-N_2 gas flow. The oxidation rate of the particles during the heating was measured from the amount of SO_2 gas evolved and the frequency factor k_0 of rate constant was estimated as 1.2x10^4 at an activation energy of 13 kcal/mol. However, the k_0-value decreased at lower heating rate and lower oxygen partial pressure.On the other hand, four kinds fo copper concentrate of different composition were fed to the top of a vertical reaction tube of 1.8 m height. The particles during the descent in the reaction tube were sampled and analyzed for S content. From the fraction desulfurized of the particles, the variation of particle temperature during the descent was calculated. The maximum particle temperature of about 1800K was attained at a position of 30 to 60 cm from the top of reaction tube, which was in agreement with the observation. The k_0-value of copper concentrate composed of CuFeS_2 was about lx10^5. Its value decreased with the amount of FeS_2 contained in the concentrate and that for the concentrate composed of Cu_9Fe_9S_<16> and Cu_5FeS_4 was about lx10^4.